Protective casing of a portable storage device



FIG. 1 is a perspective view of my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken line in FIG. 3 defines the bounds of the claimed design and forms no part thereof. 

The ornamental design for protective casing of a portable storage device, as shown and described. 